Trucks carrying Syrian forces and equipment, two tanks, and other armored vehicles have arrived in the village of Arimah in the western countryside of Manbij, sources told Anadolu Agency on Tuesday. Arimah is 25km away from the center of Manbij.

The development comes a day after Turkish-backed rebels dispatched fighters and armored vehicles to the front line along Manbij and days after Washington took an unexpected decision to withdraw troops from Syria.

Manbij is controlled by the Syrian Democratic Forces (SDF), led by the Kurdish People's Protection Units (YPG), seen as a "terrorist" group by Turkey.

Ankara says a Turkish operation in Syria will target areas under the control of YPG fighters, including Manbij.

Turkish Foreign Minister Mevlut Cavusoglu said on Tuesday that Ankara and Washington agreed to complete withdrawal of the YPG forces from Manbij before the US pulls out of Syria.

He added the US agreed to take back weapons given to the YPG, according to Al Jazeera.

Turkey was in Syria "to return the freedom of our Arab brothers and sisters, to return the freedom of our Kurdish brothers and sisters", Erdogan said in a speech.

Turkey has sent reinforcements at the border with Syria in the previous days, with local media reporting that some vehicles had crossed it.

In the past two years, Turkey has conducted two offensives into northern Syria, dubbed "Euphrates Shield" and "Olive Branch".

US President Donald Trump's surprise decision to withdraw the estimated 2,000 US troops from Syria last Wednesday has created shock among members of the Congress, including Republicans, as well as among Washington's Western allies.

Erdogan's spokesperson said on Monday that US military officials will come to Turkey this week to discuss coordination on Syria. Washington for years supported the YPG-led SDF.

A senior Syrian Kurdish official said they were reaching out for help to protect the Kurdish-administered areas against a possible Turkish offensive following the US withdrawal, adding that they were in talks with Russia, the Syrian government and European countries.